Material: 6al / 4v (tc4) titanium alloy, Grade 5. Pitch: 1.5 / 2.5 /3.0mm. Package Contents:1 pcs or 3 pcs. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object.
On the black flange nut, rainbow color in the nut hole is a normal phenomenon of the process not quality problems.